The recent LIGO event GW170817 is the merger of a double neutron star system with an associated short GRB170817A with 2.9 ± 0.3 s soft emission over 8-70 keV. This association has a Gaussian equivalent level of confidence of 5.1σ. The merger produced a hyper-massive neutron star of stellar mass black hole with prompt or continuous energy output powering GRB170817A. Here, we report on a possible detection of Extended Emission (EE) in gravitational radiation during GRB170817A: a descending chirp with characteristic time scale τs = 3.01 ± 0.2？s in a (H1,L1)-spectrogram up to 700 Hz with Gaussian equivalent level of confidence greater than 3.3σ based on causality alone following edge detection applied to (H1,L1)-spectrograms merged by frequency coincidences. Additional confidence derives from the strength of this EE. The observed frequencies below 1kHz indicate a hyper-massive magnetar rather than a black hole, spinning down by magnetic winds and interactions with dynamical mass ejecta.